Proportional control top speed limiter

ABSTRACT

A motor vehicle proportional control top speed limiter for providing a smooth entry into the speed limiting mode. A flexible contact secured at one end is oscillated by an eccentric cam driven by the speedometer drive cable. A movable contact is moved in conjunction with the indicated speed of the speedometer such that the movable contact moves into the flexible contact so as to periodically complete an electrical circuit between the movable contact and the flexible contact as the flexible contact is oscillated. The percentage time period during which the movable contact and the flexible contact complete the electrical circuit increases as the vehicle speed increases. The vehicle ignition system is disabled by the closure of the movable contact and the flexible contact to provide for proportional control top speed limiting.

United States Patent Inventors Mark Newton Culver;

Douglas E. Mark, both of Davison, Mich. Appl. No. 14,078 Filed Feb. 25, 1970 Patented Aug. 24, 1971 Assignee General Motors Corporation Detroit, Mich.

PROPORTIONAL CONTROL TOP SPEED LIMITER 2 Claims, 1 Drawing Fig.

3,356,082 12/1967 Jukes ABSTRACT: A motor vehicle proportional control top speed limiter for providing a smooth entry into the speed limiting mode. A flexible contact secured at one end is oscillated by an eccentric cam driven by the speedometer drive cable. A movable contact is moved in conjunction with the indicated speed of the speedometer such that the movable contact moves into the flexible contact so as to periodically complete an electrical circuit between the movable contact and the flexible contact as the flexible contact is oscillated. The percentage time period during which the movable contact and the flexible contact complete the electrical circuit increases as the vehicle speed increases. The vehicle ignition system is disabled by the closure of the movable contact and the flexible contact to provide for proportional control top speed limiting.

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BY Fouglas 6. Mark 76% T AT ORNEY PROPORTIONAL CONTROL TOP SPEED LIMITER This invention relates to top speed limiting and specifically to a proportional control top speed limiting.

A motor vehicle operating under full throttle conditions will reach its maximum speed when the road load and wind resistance power requirement exactly equals the power capabilities of the vehicle engine. If it is desired to limit the top speed of the vehicle to some arbitrary lower value, it is necessary to remove the excess power from the vehicle engine at the desired top speed. This excess power is defined as the difference between the power developed at the desired top speed and the power required to maintain the vehicle at the desired top speed.

The excess power may be removed from the vehicle engine in any one of several ways, such as redesigning the engine to reduce power output, controlling transmission slip on automatic transmission cars, restricting fuel input at the desired speed, or interrupting the ignition signal at the desired speed.

Redesigning the vehicle engine to reduce power or controlling the transmission slip on automatic transmission cars would seriously affect the performance and cost of the system.

When the engine parameters of fuel or ignition are controlled by a snap action type of switch and the vehicle is driven into the limit zone at wide open throttle, violent surging results. This causes severe passenger discomfort and is very harmful to drive line components. If the engine parameters such as fuel or ignition are controlled by a control switch which is closed momentarily at the desired top speed and then opened for a longer period and closed again with increasing duty cycle proportional to vehicle road speed, violent surging resulting from the vehicle going into the top speed limit zone would be minimized and therefore the passenger discomfort and the injury to drive line components will also be minimized.

The general object of this invention is to provide for a proportional control top speed limiter.

It is another object of this invention to provide for a top speed limiter in which sustained operation in the speed limiting mode will have no detrimental affect upon the vehicle engine or drive train.

it is another object of this invention to provide for a vehicle speed limiter in which the entry into and operation during the speed limiting mode shall be smooth and not cause passenger discomfort.

It is another object of this invention to provide for a vehicle top speed limiter in which the engine speed and vehicle performance will not be affected at speeds below the limit speed.

These and other objects of this invention are accomplished by inhibiting the ignition system of the motor vehicle for increasingperiods of time as the vehicle approaches the desired top speed.

The invention may be best understood by reference to the following description of a preferred embodiment and the schematic drawing of a preferred embodiment of this invention.

Referring to the Figure, a conventional vehicle speed indicating device generally designated is comprised of a magnet 12 secured to one end of an input shaft 14 for rotation therewith. The input shaft 14 has a rotational speed corresponding to the vehicle speed and may be connected, for example, by way of a flexible cable to a vehicle wheel. The speed-indicating device 10 is also comprised of a speed cup 16 and a field plate 18. A spindle 20 and an indicating needle 22 are attached to the speed cup for rotation therewith. A dial face 24 is suitably calibrated to indicate the vehicle speed and is positioned with respect to the indicating needle-22 so as to indicate the vehicle speed. The speed cup 16, the spindle 20 and the indicating needle 22 are biased against rotation by a spring 26. When the input shaft 14 and the attached magnet 12 are rotated at a speed corresponding to the vehicle speed, the speed cup 16 and the spindle 20 are rotated against the return force of the spring 26 so as to position the indicating needle 22 on the dial face 24 to indicate the vehicle speed.

To provide for speed limiting, an eccentric cam 28 is rotated by the input shaft 14. A cam follower 30 is mounted on a stationary frame member (not shown) so as to pivot about the pivot members 32 and 34. An arm 36 of the cam follower 30 bears against the cam 28 so as to transfer the cam action to the arm 38 of the cam follower 30. A flexible contact 40 secured at one end is arranged over the arm 38 of the cam follower 30 and is oscillated thereby upon the rotation of the eccentric cam 28. A movable contact 42 is secured to the spindle 20 for movement with the speed indicating needle 22.

The relative positions of the flexible contact 40 and the movable contact 42 are such that as the spindle 20 is rotated by increasing speed, the movable contact 42 moves toward engagement with the flexible contact 40. The movable contact 42 is positioned on the spindle 20 such hat as the vehicle approaches the desired top speed, the movable contact 42 moves into the flexible contact 40 so that they just touch at the low position of the cam 28. Thereafter, as the cam 28 is rotated by the input shaft 14, the flexible contact 40 moves into and out of engagement with the movable contact 42. If the speed of the vehicle is increased, the movable contact 42 moves further into the flexible contact 40 to increase the percentage time of contact during each rotation of the cam 28.

The flexible contact 40 is electrically connected between a primary coil winding 44 and the breaker contacts (not shown) of the vehicle ignition system. The remaining side of the primary coil winding 44 is connected to the positive terminal of a vehicle battery 46. A secondary coil winding 48 is connected between the distributor (not shown) of the vehicle ignition system and ground. The movable contact 42 is electrically connected to ground. As can be seen, during the time period when the flexible contact 40 and the movable contact 42 are engaged, the vehicle distributor is shorted to ground to thereby disable the vehicle ignition system.

As the vehicle speed is increased, the flexible contact 40 and the movable contact 42 do not engage one another until a speed is attained at which the movable contact 42 moves into the oscillating flexible contact 40 so that they just touch at the low position of the cam 28. Until this event occurs, the vehicle operation is in no way affected by the top speed limiter. Upon the occurrence of this event, the distributor is periodically shorted at a frequency corresponding to the rotation of the cam 28 to disable the vehicle ignition system with a resulting decrease in the power capability of the vehicle engine. As the vehicle speed is further increased, the percentage time period during which the movable contact 42 and the flexible contact 40 disable the vehicle ignition system increases proportionately with a resulting proportional decrease in power capability of the vehicle engine. The vehicle speed will increase until the power capability of the vehicle engine has decreased to a value which exactly equals the road load and the wind resistance power requirement.

As can be seen, the top speed can be selected by positioning the movable contact 42 on the spindle 20 so as to set the speed at which the flexible contact 40 engages the movable contact 42 or by adjusting the position of contact 40.

Although the foregoing description of a preferred embodiment described a vehicle speed limiter, it is not limited thereto. As will be obvious to one skilled in the art, the described speed limiter may be utilized to limit the speed of an engine in a proportional manner by making the speed of the input shaft 14 a function of engine speed and calibrating the speed indicating device 10 and the dial face 24 in terms of engine r.p.m.

What has been described is a proportional control speed limiter in which the entry into and the operation during the speed limiting mode is smooth to ensure maximum passenger comfort, in which sustained operation in the speed limiting mode has no detrimental afiects upon the vehicle engine or drive train, and in which the engine speed and performance are not affected at speeds below the limit speed.

What is claimed is:

1. A top speed limiter for limiting the top speed of a motor vehicle comprising, in combination, shaft means having a rotational speed corresponding to the vehicle speed; speed indicating means having a displacement responsive to the rotational speed of the shaft means to indicate the vehicle speed; a first electrical contact connected to the speed indicating means for movement therewith; a cam connected to the shaft means for rotation therewith; a second electrical contact positioned for contact-making engagement with the first electrical contact; and means for cyclically shifting the second electrical contact in contact breaking direction in response to the rotation of the cam, whereby electrical contact is made in momentary pulses having an average time increasing with an increase in the speed of the vehicle as the speed approaches that of the desired top speed, the first and second electrical contacts being connected in a series circuit in parallel with the breaker contacts for shorting the breaker contacts when the first and second contacts are engaged to render the ignition system inoperable for the time of engagement to provide for proportional top speed limiting.

2. A top speed limiter for limiting the top speed of a motor vehicle comprising, in combination, shaft means having a rotational speed corresponding to the vehicle speed about a first axis; speed-indicating means having an angular displacement about a second axis responsive to the rotational speed of the shaft means to indicate the vehicle speed; a first electrical contact connected to the speed-indicating means for movement therewith; a cam connected to the shaft means for rotation therewith; a cam follower, the cam follower having a first arm engaging the cam and a second arm, wherein the second arm is cyclically oscillated in response to rotation of the cam; and a second electrical contact positioned for contact-making engagement with the first electrical contact, the second arm being also engageable with the second electrical contact to shift the same cyclically in contact-breaking direction; whereby electrical contact is made in momentary pulses having an average time increasing with an increase in the speed of the vehicle as the speed approaches that of the desired top speed, the first and second electrical contacts being connected in a series circuit in parallel with the breaker contacts for shorting the breaker contacts when the first and second contacts are engaged to render the ignition system inoperable for the time of engagement to provide for proportional top speed limiting. 

1. A top speed limiter for limiting the top speed of a motor vehicle comprising, in combination, shaft means having a rotational speed corresponding to the vehicle speed; speed indicating means having a displacement responsive to the rotational speed of the shaft means to indicate the vehicle speed; a first electrical contact connected to the speed indicating means for movement therewith; a cam connected to the shaft means for rotation therewith; a second electrical contact positioned for contact-making engagement with the first electrical contact; and means for cyclically shifting the second electrical contact in contact breaking direction in response to the rotation of the cam, whereby electrical contact is made in momentary pulses having an average time increasing with an increase in the speed of the vehicle as the speed approaches that of the desired top speed, the first and second electrical contacts being connected in a series circuit in parallel with the breaker contacts for shorting the breaker contacts when the first and second contacts are engaged to render the ignition system inoperable for the time of engagement to provide for proportional top speed limiting.
 2. A top speed limiter for limiting the top speed of a motor vehicle comprising, in combination, shaft means having a rotational speed corresponding to the vehicle speed about a first axis; speed-indicating means having an angular displacement about a second axis responsive to the rotational speed of the shaft means to indicate the vehicle speed; a first electrical contact connected to the speed-indicating means for movement therewith; a cam connected to the shaft means for rotation therewith; a cam follower, the cam follower having a first arm engaging the cam and a second arm, wherein the second arm is cyclically oscillated in response to rotation of the cam; and a second electrical contact positioned for contact-making engagement with the first electrical contact, the second arm being also engageable with the second electrical contact to shift the same cyclically in contact-breaking direction; whereby electrical contact is made in momentary pulses having an average time increasing with an increase in the speed of the vehicle as the speed approaches that of the desired top speed, the first and second electrical contacts being connected in a series circuit in parallel with The breaker contacts for shorting the breaker contacts when the first and second contacts are engaged to render the ignition system inoperable for the time of engagement to provide for proportional top speed limiting. 